The aims of this project are: 1) to get a better understanding of the mechanisms maintaining fear behaviors, specifically those related to dental fear, 2) to evaluate and compare those components of the therapeutic process which will optimize the ability of therapists to select the most appropriate therapeutic modality for various types of fearful patients, and 3) to attempt to relate the etiological factors associated with the development and maintenance to more successful therapeutic outcome. The project comprises two studies. In study 1, 120 severely fearful dental patients will be subjected to an experimental investigation of their physiological reactions to dental stimuli. Patients with a history including traumatic experiences (A) will be compared to patients where the fear is related to social learning (B), to test the hypothesis that dental fear is maintained by two different mechanisms, which are classically conditioned emotional responses and unfavorable cognitions of dentistry, respectively. The 120 patients will then be allotted to one of three different therapies (Study 2), 20 patients of type A and 20 of type B to each therapy. The first therapy is aimed at the elimination of conditioned physiological activation in dental situations, the second therapy variant actualizes and changes the patient's faulty cognitions, and the third one is a combination of the two others. After therapy changes in physiological activation upon dental stimulation will be assessed by repeating the experiment in Study 1; these changes will be related to therapeutic outcome. In addition to physiological registrations (vasodilation/vasoconstriction, heart rate, surface EMG and skin conductance activity) the patients will be followed by psychometric questionnaires as well as overt behavioral measurements. The psychometric instruments investigate areas of dental and general anxiety and fear reactions, emotional factors like depression, mood and tension before and during treatment, and attitudes towards general health, dentistry and treatments. The behavioral measurements include an approach test and dentist ratings of patients' treatment ability. Emotional facial expressivity will also be assessed during therapy. The project will promote a finer understanding of fear reactions in individual cases. It will also increase our ability to help individuals get rid of handicapping fear responses, specifically in relation to dentistry.